2022 Sep 26. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–.
Pleural effusion is a common occurrence in emergency departments (ED) worldwide and a constant reason for a pulmonology consultation. In the United States, nearly 1.5 million cases of pleural effusion are diagnosed each year. Congestive heart failure (CHF) is the most common cause, followed by pneumonia. Traditionally, pleural effusions are divided into transudate and exudate. Transudate implies an intact capillary membrane but increases hydrostatic pressure due to fluid overload. Exudative effusion is a result of capillary damage secondary to an inflammatory process.
Pleural effusions can be treated with thoracentesis, and they do not recur if the underlying cause is corrected. However, a significant number of effusions do not resolve or, if treated, come back very quickly. These types of effusion cause a significant healthcare burden, and they are very uncomfortable for the patient and difficult for caregivers.
Malignant pleural effusions (MPE) are the most common among these refractory pleural effusions. Lymphoma, breast and lung cancers are the leading cause of MPEs. Among non-malignant pleural effusions, CHF and hepatic-hydrothorax are most common.